1. Field of the Invention
The present invention relates to a non-reciprocal circuit device, such as an isolator, a circulator, or other suitable device, used in a microwave band and a communication apparatus including such a non-reciprocal circuit device.
2. Description of the Related Art
An example of a known lumped-constant-type isolator used in mobile communication apparatuses such as portable telephones, and other suitable communication apparatuses, is described in Japanese Unexamined Patent Application Publication No. 11-195912. As shown in FIG. 12, the isolator 200 includes a terminal resin case 202, a lower metal case 208, and an upper metal case 204, and a permanent magnet and a central-electrode assembly provided in the terminal resin case, although not shown.
In FIG. 12, an input-output terminal 210 and a ground terminal 211 for surface mounting are provided on a side wall 202a on the front surface of the terminal resin case 202. An input-output terminal and a ground terminal are also provided on a side wall 202a on the rear surface of the terminal resin case 202, although not shown.
As shown in FIG. 12, the isolator 200 is produced using a lead frame 231 in order to facilitate handling of the product in production and automation of the production. The lead frame 231 is successively transported from one assembling process step to another via pilot holes 234 provided in each of a pair of hoop portions 233. While the lead frame 231 is transported from one assembling process step to another, the ground terminal 211 and the input-output terminal 210 are insert-molded in the terminal resin case 202. A connection portion 235 is provided on the bottom portion (side of the substrate for mounting the isolator 200) of the side wall 202a of the terminal resin case 202 to facilitate mounting of components in later steps. Then, the components (upper metal case 204 and lower metal case 208) of the isolator 200 are mounted, and the isolator 200 is assembled. The isolator 200 is separated from the lead frame 231 by stamping out the connection portion 235, which connects the lead frame 231 with the isolator 200 and by using a cutting die.
However, as shown in FIG. 12, since the isolator 200 is separated from the lead frame 231 by stamping out the connection portion 235 provided on the side wall 202a of the terminal resin case 202, burrs are produced on the cutting surface of the connection portion 235. When these burrs are present, mounting conditions of the isolator 200 deteriorate because a gap caused by the burrs exists between the isolator 200 and the mounting substrate. For example, the mounting anchorage of the isolator deteriorates, and the terminals 210 and 211 are separated from the connection electrodes of the mounting substrate, which produces an open circuit.
Furthermore, since the terminals 210, 211 and the connection portion 235 are provided on the side wall 202a of the terminal resin case 202, the width of the input-output terminal 210 and the grounding terminal 211 is reduced because the connection portion 235 is provided on the side wall 202a, and the solder joint area of the mounting substrate and the input-output terminal 210 and grounding terminal 211 is reduced. Therefore, when the isolator 200 is mounted on a mounting substrate, the mounting anchorage of the input-output terminal 210 and grounding terminal 211 deteriorates.
In order to overcome the problems described above, preferred embodiments of the present invention provide a non-reciprocal circuit device which provides greatly improved mounting anchorage, reduced size, and outstanding reliability, and a communication apparatus including the non-reciprocal circuit device.
According to a preferred embodiment of the present invention, a non-reciprocal circuit device includes a permanent magnet, a ferrite member having a DC magnetic field provided by the permanent magnet and a central electrode assembly including a plurality of central electrodes arranged around the ferrite, a terminal resin case including the center electrode assembly, the terminal resin case having a first side surface defining a cutting surface when the terminal resin case is separated from a lead, input-output and ground terminals which are led out from a second side surface, different from the first side surface of the terminal resin case, and a metal case which includes the permanent magnet and the terminal resin case.
Accordingly, since the cutting surface, formed when separated from the lead frame, is provided on the first side surface of the terminal resin case and the input-output and grounding terminals are provided on the second side surface, which is different from the first side surface, of the terminal resin case, the width of the input-output and grounding terminals is greatly increased and the solder joint area of the substrate for mounting and each of the terminals is greatly increased.
Furthermore, preferably, a grounding electrode plate that is separated from the lead frame at the cut surface is integrally provided with the terminal resin case, and the grounding electrode plate extends to define the ground terminal. In this way, the ground potential of the grounding electrode plate integrally provided together with the ground terminal is reduced, and stray inductance which does not contribute to the operation of a non-reciprocal circuit device is minimized.
Furthermore, preferably, a concave portion is provided on the side surface of the terminal resin case, the cut surface is disposed in the concave portion, and the cut surface is covered by the metal case. In this way, when the non-reciprocal circuit device is separated from the lead frame, the positional accuracy for separation is less important. That is, even if the position for separation deviates slightly, the left portion is received in the concave portion and will not protrude outside of the dimensions of the non-reciprocal circuit device. Furthermore, even if burrs and metal chippings exist on the cut surface, the cut surface is still covered by the metal case, and thus, a short circuit and an open circuit are not caused.
Furthermore, preferably, an insertion hole is provided in the grounding electrode plate so as to insert the central-electrode assembly. That is, since a portion of the central-electrode assembly is included in the grounding electrode plate, the height of the non-reciprocal circuit device is reduced by the thickness of the grounding electrode plate.
Furthermore, since a communication apparatus according to the present invention includes a non-reciprocal circuit device according to preferred embodiments described above, a smaller, a less expensive and more reliable apparatus is provided.
Other feature, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.